Donald Trump. Picture: REUTERS
Donald Trump. Picture: REUTERS

To hear the justice department tell it, six years ago California announced it was going to violate the US constitution — and nobody noticed until now. That, at least, is the argument President Donald Trump’s administration has made in a lawsuit that’s part of its larger campaign to punish California for its climate leadership.

At issue is the deal California struck with Quebec in 2013, establishing a joint cap-and-trade programme. Negotiated with bipartisan support, the programme has reduced carbon emissions while adding billions to public coffers on both sides of the border. The carbon market it created has worked as intended, and other countries see it as a model.

Does creating a carbon market with a Canadian province amount to conducting “independent foreign policy”? That’s the justice department’s claim: The pact, it says, is a treaty violating article I of the constitution. “California has veered outside its proper constitutional lane,” a department official said.

Few noticed this constitutional atrocity back in 2013. The state’s ban on foie gras was a bigger controversy that year. But it’s no surprise it has burst into view now — as the Trump administration lodges attack after attack after attack on California, many plainly dubious, designed to keep it from setting environmental standards stricter than Washington’s.

The case reeks of bad faith. The crux of the justice department’s argument is that the California-Quebec pact “undermines the president’s ability to negotiate competitive agreements”. Trump has no plan to negotiate a better cap-and-trade deal. He just wants to shut this one down.

The court will decide whether the pact is an illegal treaty or a lawful memorandum of understanding, as its designers contend. If the administration wins, California and Quebec could continue to run their carbon markets independently — a less efficient set-up that would raise costs for businesses and consumers.

But the greater danger is that the lawsuit will forestall other efforts by cities and states to co-operate in fighting climate change. Right now, with a federal government determined to make no such efforts, such agreements are desperately needed.

Hundreds of cities have pledged to honour the Paris agreement on climate change, and states are banding together to cut emissions and push back against the administration’s overreach. They should keep it up. And California should be applauded for standing up to a climate bully.

Bloomberg